The rapid rise of the Assunpink Creek, which flows next to the tracks near the Trenton station, left 16 SEPTA cars stranded. Four were on tracks far enough north to avoid flood damage and have been returned to service.
But the other 12 incurred extensive corrosion and damage to their electrical motors, said Luther Diggs, SEPTA's assistant general manager of operations. He said it might take weeks or months to repair the cars and return them to service. He did not estimate how much the repairs would cost.
"It's not going to be easy," Diggs said. "We're digging into it now. We did see a lot of corrosion. Those cars sat up there a long time."
Diggs said the absence of the cars would not cause much overcrowding for SEPTA passengers because newly arrived Silverliner V cars are beginning to ease SEPTA's chronic shortage of cars.
"It should be invisible to our passengers," Diggs said.
Diggs said SEPTA relied on previous storm experience in assuming it could safely leave the cars in Trenton during Hurricane Irene.
And five of the cars would have left on regularly scheduled runs to Philadelphia hours before Irene hit if Amtrak had not halted all train service on that section of the Northeast Corridor shortly before the trains were scheduled to depart, Diggs said.
Amtrak and NJ Transit stored out-of-service trains at their rail yard in Morrisville and they escaped damage, but SEPTA does not have a nearby yard.
Ron Hopkins, SEPTA's chief control center officer, said SEPTA officials had tracked National Weather Service predictions for a number of creeks in SEPTA's service area, and moved railcars and other vehicles out of the way, following standard pre-storm procedures.
But the Assunpink was not one that SEPTA was watching.
The creek, which is normally less than four feet deep, crested at 15.1 feet after Irene, setting a record, Hopkins said. As recently as 2007, the stream had risen to 13 feet without causing a problem, he said.
The creek crested at 14.6 feet in a 1976 storm, but that was before SEPTA took over operations of the railroad.
"The Assunpink never has been on our radar screen before," Diggs said. "It just came out of nowhere."
If they had it to do over again, SEPTA officials said, they would have moved the cars to a Philadelphia-area yard before the storm, or shifted them north to the Ham Interlocking area, where the other four cars remained above water.
Contact staff writer Paul Nussbaum at 215-854-4587 or email@example.com.